12v Charging Problems - Regulator??

Submitted: Tuesday, Apr 07, 2015 at 12:08
ThreadID: 117373 Views:1833 Replies:3 FollowUps:3
This Thread has been Archived
I have recently purchased 3 x 120AH AGM deep cycle batteries. I have 2 x 200w solar panels on the shed roof (nearly 5yrs old). I have calculated my daily amp hour use at about 70ah/day. (Water pump, Waeco HD220 upright fridge, Radio running through the inverter, LED lights.) I have boosted my stored power so I can run a 12v TV and a stereo off the inverter. These items are not hooked up yet, but when they are, I expect my usage would be about 100ah/day. All the calculations I have done seem to suggest that 400w of panels should be ample to keep the the batteries charged as I only want to draw down 30-40% of the batteries.
The solar reg was a cheap chinese ebay job (nearly 5yrs old).
My problem is that over the last week since I connected the new new batteries, they are not charging much at all. I have had good sunlight (Bridgetown WA). but at the end of the day they are showing 12.4 - 12.6v. This morning they were down to 11.5v!
The solar reg display shows that during the day I am getting good volts from the panels (VpV?), but the power going into the battery (IPV??) is very low. Reading less than 2-3 during a sunny day.
My uneducated brain is telling me that the panels are working? but the power is not flowing to batteries, hence the slow loss of power over the last week.
QUESTION TO THE GURUS OF 12v - Should I buy another 200w panel to be sure to be sure? Should I buy a new Solar Regulator (MPPT?) or Should I buy both?
Can the batteries be discharging somehow? leakage?
Looking forward to some help, as I don't want to bugger up $1000 worth of batteries.


Back Expand Un-Read 0 Moderator

Reply By: HKB Electronics - Tuesday, Apr 07, 2015 at 13:08

Tuesday, Apr 07, 2015 at 13:08
Shouldn't be to hard to work out where the problem lies, if you have 400 Watts of panels, the batteries are in a low state of charge and you have a bright sunny day you should see around 20+ amps flowing into the batteries if not the regulator has a problem.

Is it set to the correct type of battery and charge mode etc, if so then possibly it is faulty.

Lifetime Member
My Profile  Send Message

AnswerID: 552092

Reply By: Bob Y. - Qld - Wednesday, Apr 08, 2015 at 13:35

Wednesday, Apr 08, 2015 at 13:35

$1000 of batteries being run by a "cheap eBay regulator" is a bit like buying a new 200 series Landcruiser, and running it on old cooking oil from Pauline's fish shop.

Like HKB said you should be getting 20 amps plus from your panels, so maybe get an MPPT reg first, and go from there. Whether you need a 3rd 200 w panel would be question for the gurus, which I'm not. If you added another panel, you'd probably need more than a 30 amp reg too.

You can save more power by ditching the inverter to run your radio. 12v car radio head units are cheap as these days, and it's not hard to get a Sony, Pioneer etc. with 50w/channel, for less than $200. If you want stereo as well, just get a pair of bookshelf speakers, or better still, something with 10" or 12" woofers, mid range & tweeters, and you'll have all the bass you'll need. At least you'll be rid of the inverter losses.

Wouldn't hurt to recheck all the wiring too, to make sure there isn't a simple problem causing your dramas.

Good luck,

Seen it all, Done it all.
Can't remember most of it.

Lifetime Member
My Profile  My Blog  My Position  Send Message

AnswerID: 552154

Follow Up By: Kenny73 - Thursday, Apr 09, 2015 at 11:56

Thursday, Apr 09, 2015 at 11:56
Thanks for the advice. New Reg about to be ordered, new 7 stage battery charger purchased and charging batteries!

Spot on with the Stereo, i was thinking of a good car stereo and 4x 6x9in speakers.
FollowupID: 837783

Follow Up By: Bob Y. - Qld - Thursday, Apr 09, 2015 at 13:20

Thursday, Apr 09, 2015 at 13:20
Check out this link below, Kenny. Might be what you need?

I made an older version that they published, before CD's came into use, and it worked well, even with an "el-cheapo" head unit.

Mini Entertainment Centre

You can quite often get a kit, head unit and speakers, which seem to work out much cheaper than buying separate components. Have only seen these at JB HiFi, which might be a bit scarce where you live?


Seen it all, Done it all.
Can't remember most of it.

Lifetime Member
My Profile  My Blog  My Position  Send Message

FollowupID: 837789

Reply By: Member - John and Val - Wednesday, Apr 08, 2015 at 15:05

Wednesday, Apr 08, 2015 at 15:05

You quote "good volts" (VpV) from the panels. Just what reading are you getting? If it's a non-MPPT type of controller and it's ok I'd expect maybe 13-15 volts with the batteries so far down. With MPPT it should be up around 17-18V. In both cases if the controller is ok you should be getting about 20A from the panels in good sunlight.

Now ..... just a thought. Are your 200W panels the sort used on the roof of your house or are they suitable for battery charging? The two are not interchangeable.

Suggest measure the panel output voltage (disconnected from the controller) and the short circuit panel current ( again disconnected from the controller), and let us have those numbers. We want them to be about 22-24 volts and 20 amps. Most certainly, don't buy more panels at this time.

Another suggestion - for the sake of your new batteries, fully charge them asap using a 240v mains charger.



J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein

Lifetime Member
My Profile  My Blog  Send Message

AnswerID: 552159

Follow Up By: Kenny73 - Thursday, Apr 09, 2015 at 12:03

Thursday, Apr 09, 2015 at 12:03
Good advice! 99.99% sure the reg is dead. Panels are for battery charging. Batteries are on 240v charger as we speak, while i wait for a new reg.
Will check the output voltage.
Appreciate the help
FollowupID: 837785

Sponsored Links